1. Technical Field of the Invention
The invention relates to punch presses wherein an electro-magnetic driving force is employed. In particular, the invention relates to means for achieving a maximum magnetic driving force by the time the moving elements of the press are put into motion.
2. Prior Background Art
Electro-magnetic punch presses are well known. Unfortunately, all known punch presses of this type suffer a common fault. That fault lies in the fact that the moving elements of the press are induced to move by the magnetic field before the magnetic core is fully magnetized and the magnetic field has reached its peak energy level. Thus, the punch elements are induced to move in a relatively sluggish manner. Since force is determined by the mass and the acceleration provided that mass, it may be readily realized that the faster the punch elements are accelerated, the greater the force applied by the punch.
Several factors influence the ability to rapidly accelerate the punch elements. In the prior art much of the machine itself forms part of the magnetic path through which the energy passes in energizing the punch coil. This dilutes the energy which is best isolated to the electro-magnetic coil itself. Further the faster the rise time of the electro-magnetic energization pulse, the less the depth of the core material which is utilized to immediately drive the magnetically driven element.
It is an objective of the present invention to more fully isolate the magnetic field than has been achieved in prior art devices. Most importantly is an objective of the invention that the adverse ramifications of skin effect will be avoided such that a rapidly rising energization pulse may be employed and permit the full depth penetration of the magnetic's core by the electro-magnetic wave thereby generated.